Hi! I'm new to OpenStack (and Linux as well) and I'm trying to get DevStack installed and working. I have already managed to create an image, but I'm not able to create an instance from it. I got error "Host not found" so I navigated to System Information to prove that nova-compute isn't running. So, I run "sudo nova-compute" after which nova-compute appears but soon goes to state "down". I get the following errors:

WARNING nova.compute.manager [req-abc None None] While synchronizing instance power states, found 0 instances in the database and 1 instances on the hypervisor.
WARNING nova.compute.manager [req-abc None None] Bandwidth usage not supported by hypervisor.
2015-06-04 07:37:33.739 ERROR nova.virt.libvirt.host [req-abc None None] Connection to libvirt failed: Failed to connect socket to '/var/run/libvirt/libvirt-sock': No such file or directory
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host Traceback (most recent call last):
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/opt/stack/nova/nova/virt/libvirt/host.py", line 531, in get_connection
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     conn = self._get_connection()
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/opt/stack/nova/nova/virt/libvirt/host.py", line 518, in _get_connection
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     wrapped_conn = self._get_new_connection()
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/opt/stack/nova/nova/virt/libvirt/host.py", line 470, in _get_new_connection
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     wrapped_conn = self._connect(self._uri, self._read_only)
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/opt/stack/nova/nova/virt/libvirt/host.py", line 321, in _connect
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     libvirt.openAuth, uri, auth, flags)
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 141, in proxy_call
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     rv = execute(f, *args, **kwargs)
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 122, in execute
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     six.reraise(c, e, tb)
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/usr/local/lib/python2.7/dist-packages/eventlet/tpool.py", line 80, in tworker
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     rv = meth(*args, **kwargs)
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host   File "/usr/local/lib/python2.7/dist-packages/libvirt.py", line 105, in openAuth
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host     if ret is None:raise libvirtError('virConnectOpenAuth() failed')
2015-06-04 07:37:33.739 TRACE nova.virt.libvirt.host libvirtError: Failed to connect socket to '/var/run/libvirt/libvirt-sock': No such file or directory
2015-06-04 07:37:33.739 TRACE nova ...